The aorta is the largest artery in the body. It carries blood from the heart to the rest of the body. This thick vessel rises out of the heart (aortic root and ascending thoracic aorta) and bends back downward (aortic arch) and through the chest (descending aorta) before extending into the belly (abdominal aorta).
An aortic dissection is a tear or split within the inner lining of the aorta wall. When blood enters this split, the wall separates (dissects) and creates a pocket that traps blood.
Dissection can cause clotting, disrupt blood flow into aortic branch vessels (supplying the heart, brain, kidneys or intestines), or rupture and cause internal bleeding. The underlying cause of dissection is a weakness in the middle layer of the aortic vessel. The weakness could be due to an inherited connective tissue disease but more commonly is due to high blood pressure, atherosclerosis, a weak bulge on the aorta (aneurysm) or an aortic valve defect.
There are two types of aortic dissection:
- Type A dissection begins in the ascending aorta and progresses throughout the vessel, often extending as far as the arteries in the leg.
- Type B dissection involves a tear that is located only in the descending aorta but may extend into the abdomen.
It’s important to know the distinction between the two types of dissection as it will guide treatment.